Filtration



United States Patent [111 3,537,5

[72] Inventor Luzlo Dfllttll' 2,170,180 8/1939 Youker 2l0/268X 2Budapest, Hungary 2,863,829 12/1958 l-lenke et 31.... 2l0/33X [2|] Appl.N0. 622,551) 3,238,125 3/1966 Mihara et al... 210/268X [22] Filed March13, 1967 l,l30,382 3/1915 Deacon etal 2l0/l89 [45] Patented Now-3, 1970r FOREIGN PATENTS 474,615 12/1914 France 210/268 632,786 12/1961 Canada210/268 11 Britlsll Company [32] priority Mn 2 1965 PrimaryExaminer-Saturn N. Zaharna [33] Hungary Attorney?- Norris & Bateman [31]N0- DE-SG [s4] ABSTRACT- A li uid 11116: cm risin a container a li uid6chhm4nnwl" inlet leading into said container and 5 liquid outletleading [52] 11.5. from said container, thearrangement being such thatin the i 8 operation of the filter a substantially continuously moving 1Ill-cl 5" body of discrete filter particles is provided through which[50] Search "1 210/33, I liquid to be filtered passes, transversely fsaid body, in 139,263 passing from the inlet to the outlet, filterparticles through a 1 which li uid has been passed are conveyed to alocality where [56] cued they areqcleaned by contacting with liquidwhich has been fil- UNITED STATES PATENTS v F tered by the body offilter particles, and the cleaned filter par- 2,057,887 10/ 1936 Elliottet al. 210/268X i e are r y led for f r her-filtr i n of liq i Sheet or2 #vmvron Lasz/o Demclbr A TTORNEYS Patented Nov. 3, 1970 3,537,582

Shoot o! 2 wmvron lasz/a Demefcr 7mm 965W s uns-non BACKGROUNDANDSUMMARY oriuvsnrion.

This invention relates to apparatus and a process for the filtration ofaliquid.

Contaminations suspended in surface water and particularly in riverwater has ',b eenremoved according to previously proposed arrangements,by sedimentation followed by purification. in such arrangementsfiltration is effected through horizontally arranged filter layershaving ,a-thicltnessgof l to 2 metres, the filter layers consisting ofparticles .with close size limits/The crudewater to be filtered isallowed to pass -through each filter {layer in a vertical direction,generally downwardly but sometimes upwardly. The contaminationssuspended in ,thelcrudle water are retained in the interstices betweentheparticlesastheypass through the filter layer.

A common disadvantage of such previously proposed filtration equipmentisthatthelinterstitial spaces-between the particles become saturatedwith suspended contaminations within a short period of time and thefilter layers lose their filtering power. ln order to regenerate eachfilter :layer it must be washed with amixture of-water and air blown inat the bottom. For this operation-it is necessary to interruptfiltration and thus considerablyrcduccszthe output of the aforesaidfiltration arrangements. A relatively great amount of pure water isneeded for washing :the filter particles. This is an appreciable losssince .oneof the main objects of .thearrangement is the production ofpure water. Furthermore during the washing operation large masses offilter particles must be moved and this requires-equipment-ofapprcciablecosts of investment and operatiomSuch equipment takes uplaconsiderable amount of space necessitating large buildings and expensivemachinery foroperation.

Filtration equipment ,has also been proposed where, in order to ensurecontinuous operation of the filtration process, the contaminatedparticles are sucked ,off by an injector from the bottom of a tankcontaininga filter layer. Theseparticles arethen transferred intoatankfilled with liquid where the contaminations adhering tothe filterparticles are removed by sedimentation, and the purified .ordecontaminated particles .of the liquid to be filtered through saidcolumn or columns in a direction substantially transverse to thedirection of movementof said column or columns, and means for collectingthe filtered liquid after having passed through the column or columns. I

Preferably the container has an upper part and a lower part of greatercross section than the upper part and in which lower part the column orcolumns of filter particles are adapted to be located, means forrecycling contaminated particles to the upper part of the container,meansfor effecting passage of a portion of the liquid fed to thecontainer against the downward fiow of recycled contaminated particlesto deconpassing downwards to the filter means, and means for affectingdischarge from the container of said liquid portion conlaminatedthereby.

According to a further aspect of the invention there is provided aprocess of continuously filtering a liquid comprising effectingsubstantially continuous movement of one or more columns of filterparticles in a downward direction, passing the liquid to be filteredthrough each column in a direction substantially transverse to thedirection of movement of the columnand collecting the liquid filteredthereby.

The term substantially continuous" as used herein and in the claims inrelation to the downward movement of the filter particles is intended toinclude, as well as completely continuous movement, intermittentmovement at intervals sufficiently are recycled into the filtration.tankby a secondinje'ctor. in I this type of equipment also, however,the crude water tobe filtered is passed through a'horizontally arrangedplayer of sand or other granularsubstance in a vertical direction. Suchequipment again has the disadvantage that aconsiderable amount of spaceis required and is expensive to operate due to the use of the two pumps.It is generally known that injectors operate at a very low output. 0ntaking into account the fact that great amounts of substances arerequired to be moved by the injectors at relatively high rates, it willbe apparent that water filtration of this type is an eitpensiveoperation. In addition, the contaminations are not completely removedfrom the filter material because the filter particles are transferredinto the filtration tank with the aid of unfiltered crude waten'and thismethod is therefore unsuitable for yielding completely purified ordecontaminated particles and subsequent filter layer.

. An object of the present invention is to provide a process andapparatus for the removal .ofcontaminations suspended in for-examplesurface waters and particularly river waters, whereby the filtration .ofcrude water can be continuously and successfully carried outsafely.-withoutinterruption over a considerable period oftime;e.g.,'months.

A further object of the invention is to provide an arrangement whereinthe contamination removed from the crude water by filtration can becontinuously removed from the con.- taminated filter particlessimultaneously with the filtration process.

According to the present invention there is provided apparatus forcontinuouslyfiltering a liquid comprising a container, filter meanswithin said container for permitting substantially continuous movementof one or more columns of filter particles in a downward direction andeffecting passage frequent to achieve the desiredrate of substitution ofcontaminated filter particles by clean filter particles for the filter"ing operation. a

The process and apparatusin accordance with the present invention havethe following advantages:

The liquid to be purified must pass, instead of through a filter layerof a thickness of a few metres as in conventional filtration equipment,only through a filter column of a thickness of some decimetres. Thus,the filtration rate, and the filtration output of the equipment of theinvention, considerably exceeds that of the conventional filtrationequipment. This becomes possible by applying, instead of theconventionalvertical streaming, an almost horizontal or transversedirection of flow of the liquid to be filtered through the filter columnor columns. This can be used in the equipment according to the inventionbecause the filter particles in each filter column are substantiallycontinuously replaced, and thus, the liquid to be filtered always passesthrough pratically pure particles in the filter column which serves tomaintain an etficient filtration process. Owing to the high purifyingefficiency of the equipment, the equipment according to the inventioncan be constructed in a considerably smaller size than conventionalwater purifying equipment. Consequently, the production costs are lower,the space requirements are similarly lower, and significantly smallerand cheaper buildings are required to house the equipment. The decreasein space requirementis mainly due to the fact that the filter layer isarranged in a vertical direction in the form of a column or columnsinstead of the conventional horizontal arrangement.

The cycling rate of the filter particles can be varied, quiteindependently of the actual filtration process, simply by controllingthe means e.g., pneumatic, for recycling the contaminated particles tothe upper part of the container. Thus, the equipment needs notablysmaller quantities of filter particles than conventional filtrationequipment of the same output and the quality of filter particles doesnot require to be renewed. This smaller quantity of filter particlesonly requires for its movement and recycling by pneumatic means an aircompressor of small output and low pressure. Consequently, the costs ofoperation of the equipment according to the invention are low, and thecosts of capital investment amount only to a fraction of those of theconventional'equipment.

The operation of the equipment is safe because there are no movingparts, and thusfailures are obviated or mitigated.

DRAWINGS DESCRIPTION The filter comprises a vertically elongatedcontainer 2, a liquid inlet 1 leading into the container 2, and a liquidoutlet 20 leading from the container 2. In the operation of the filter acontinuously vertically downwardly moving body of discrete sandparticles, comprising four separate continuously moving filter curtains15, is provided through which liquid to be filtered passes generallyhorizontally in passing from the inlet 1 to the outlet 20.

The inlet 1 comprises two'branches 1a, 1b (FIG. 2) which lead intospaced chambers 3, 4, respectively. The chamber 3 comprises opposedvertical walls 9, which are perforated for the passage therethrough ofwater to be filtered; and the chamber 4 comprises opposed vertical wallsll, 12 which are also perforated for the passage therethrough of waterto be filtered. The outlet comprises three branches 20a 20b, 200 whichlead from spaced chambers 16, 17, 18 respectively. The chambers l6, l7,18 comprise vertical walls 19 facing the walls 9, 10, ll, 12 of thechambers 3, 4; each wall I9 is perforated for the passage therethroughof filtered water; the walls 9, 10, ll, 12, 19 all extend vertically andhorizontally along the body of filter particles adjacent thereto. Thesand curtains 15 are provided between the adjacent pairs of chambers 3,16; 3, I7; 4, l7; and 4, 18. The perforations in each wall 9, 10, 1l, l2are inclined downwardly and are provided by inclined plates 13 (FIGS. 3and 4) which are spaced by vertical support members 33. Each perforatedwall 19 is covered by a sieve cloth 40 which prevents sand particlespassing through the wall 19. In a modification the sieve cloth 40 isomitted and the perforations in the wall 19 are themselves small enoughto prevent passage of sand particles therethrough. The chambers-3, 4,l6, l7, 18 are located in a lower bulbous portion 42 (FIG. 1) of thecontainer 2.

The container 2 comprises a vertical stem 22 which leads from thebulbous portion 42 via a constriction 23 to an upper, funnel, portion 24which is open at the top. A downwardly extending stub pipe 25 open atits upper and lower ends is provided in the funnel portion 24 and anoutlet 26 leads from the pipe 25 out of the container 2. A pipe 28 leadsfrom the lower end of the container 2 to the funnel portion 24 andenters the funnel portion 24 at a level below the upper end of the pipe25 and above the outlet 26; a pipe 30 leads from a supply of compressedair (not shown) via a flap valve or screen 32 into the pipe 28. In amodification a plurality of pipes, corresponding to the pipe 28, leadfrom the lower end of the container 2 to the funnel portion 24.

In the operation of the filter, water to be filtered enters the inlet 1from a header tank (not shown) above the level of the outlet 26, passesto the chambers 3, 4, passes through the perforated walls 9, 10, ll, 12,through the sand curtains 15, which are moving downwardly. by gravity,through the perforated walls 19 and into the outlet 20. Some water risesalong the stem 22 and, in the constriction 23 and the funnel portion 24,contacts used sand particles to clean them; water has been filteredthrough these sand particles in the bulbous portion 42 and they havebeen conveyed from the bulbous portion 42 along the pipe 28 to thefunnel portion 24; the water which has cleaned the sand particles passesto waste via the stub pipe 25 by the flap valve or screen 32. Cleanedsand particles are recycled by gravity down the stem 22 and back to thebulbous portion 42 for further filtration of water. It will be realizedthat by varying supply of air along the pipe 30 the rate of recycle ofsand can be varied independently of the flow rate of liquid through thefilter.

lclaim:

Apparatus for continuously filtering a liquid comprising a container,filter means within said container for permitting substantiallycontinuous movement of a plurality of relatively narrow columns offilter particles in a downward substantially vertical direction andeffecting passage of the liquid to be filtered through each column in asubstantially horizontal direction, said filter means comprising aplurality of units each of which includes an inlet chamber and an outletchamber having coextensive portions extending longitudinally asubstantial distance along one of said columns and defining a passagefor one of said columns of filter particles, each said inlet chamberhaving a side wall defining one side of said passage, each said sidewall comprising a series of overlapping plates inclined downwardly andtowards said passage, each said outlet chamber having a perforated sidewall defining the other side of said passage, means for supplying liquidto be filtered to each said inlet chamber for passage outwardly betweensaid overlapping plates substantially horizontally across said columnand through said perforated side wall into an outlet chamber, the inletand outlet chambers of said units being disposed alternately across thecontainer so that each inlet chamber can cooperate with a filter columnon each side of said inlet chamber, and means for collection thefiltered liquid from said outlet chambers.

2. Apparatus as claimed in claim 1, in which the container has an upperpart and a lower part of greater cross section than the upper part andin which lower part said units are located,.means for recyclingcontaminated particles to the upper part of the container, means foreffecting passage of a portion of the liquid fed to the containeragainst the downward flow of recycled contaminated particles to decon'taminate them priorto the decontaminated filter particles passingdownwardsto the filter means, and means for effecting discharge from thecontainer of said liquid portion contaminated thereby.

3. Apparatus as claimed in claim 1, comprising pneumatically operatedmeans for recycling the contaminated particles to the upper part of thecontainer and thereby effecting the substantially continuous downwardmovement of said column.

4. Apparatus as claimed in claim 3, in which the pneumaticallyoperated'means comprises a pipe interconnecting the lower part of thecontainer and the upper part of the container, and a source of pneumaticpressure connected to said pipe for effecting movement of contaminatedfilter particles up the pipe to' the upper part of the container.

5. Apparatus as claimed in claim 1, in which means is provided forrecycling contaminated filter particles which flow downwardly in saidcolumn, and means is provided for effecting passage of a portion of theliquid against the downward flow of contaminated filter particles andsuch latter means comprises a source of liquid to be filtered located ata level above the discharge of filtered liquid from the containerwhereby a sufficient head of pressure is created to effect said passageof liquid upwardly from the filter means.

6. Apparatus as claimed in claim 5, comprising a restriction throughwhich said portion of liquid can pass, said restriction acting toincrease the velocity of the liquid flowing against the contaminatedparticles.

